Floating roof for liquid storage tanks



Patented YJ an. 25, 1949 lohmH. v'ldiggina C hicago, Ill.

"Applicationctober 12, 1944,Seriall No. '558,393

i 31 lafim.

*'his -invention relates to'fiioati'ng Ytank roofs, 'nfryf presentapplication being VVa ffcontinuation, in part; `'o'f my pendingapplication Serial "No. 't5d0;27?8, filed Aug-ust. Vi9, 1944, v'now'Patent "No '2,425,7'7-1pdated Augustl'l, f194'7.

i In'mysaid--pendingapplication I-havedisclosed a floating tank roof,comprising a `rigid/center pontoon,^ -provide'd with -a peripheralsrirnalexible deck portion* surroundingl usaid cent-er pontoon, and attachedat its inner edge to the loweren'dof the `rimof said Ycenter pontoon, aystiff vannular member attached-tothe peripheral or outer edge 'of tlredeck `portion, and designed so as to take compressionicirciunierentially, and radially-'disposedtrusses or anequivalent'm-eans `combined with vsaid ,annular cornpressionxmembenandwith said 'centerpontoonLinsuch ,a waylthat aportion of the weight 'ofsaid annularompres'sion meiniberis applied to the rim ,of 'the v centerpontoon, thereby conc entrating. alheavyloadon the center pontoonandzsiibrnerglng therim. @of esame-in fthe roof supporting liquid, .,to.a depth -su'fcient vt0 .cause '.,the deck portion to slope.downwardly@- Wards thecenterothe roof., Witha progressively increasing,pitchias it approaches itlie rim-of the center pontoon, Wherebythedeclrportionfwlillabe maintained in a condition or position thatcinsuresrapid ffandfiflcient `drainage of same. In the particular embodiment ofVmy basic idea illustrated in thedrawingssoiimyzsaid pendingapplication, the annnlarcoinpinssion memberto which the `outeredgebf'the 'deck porti'ronjissattached, consists of a stiff annularpontoon. "Such a construction islhighlyidesinableilorroofs of relativelygreat diameter, but for smaller roofs, for examplc,:1eos having adiameter-of.approximately 6) tnor-rless, git is not essentialthatthe'iarirlfular no inpression member at the peripheraleedge :of theroofconsist of apontoon. y

`Lnzthe\,r,o.or` herein di scloscd,jthe compression meniberatoiwhichthe.periphena-l.;edge ofathezdeck portion :oi ithe ,roof .is attached,consists yfof Hran annulariplatagirder, ,thatproifectsfupwardlyfrom theperipheral edge of the deck portion of the roof. Any suitable means may.beused to transier part of the weight of said annular plate girder tothe peripheral rim of the center pontoon to sink said rim deeper in theliquid on which the roof floats, but in the preferred form of myinvention herein illustrated, the means employed for said purposeconsists of a plurality of radiallydisposed tension rods attached attheir outer lower ends to the lower edge portion of said plate girder,and attached at their inner, upper ends i i2 sothat-:waterwhich fallsonto saniepor ywhichls created bythe `melting volsn-ow that hascollected on-thetop cfthecenter pontoon, will drain to one or moreoutlets inthe center pontoon that discharge ydownwardly into the liquidon which the roof oats, or which are connected with'one or more suitable-eduction pipes of conventional construction, that depend fronitheunderside of thecenterpontoon and lead to the exterior of the'tankPreferably, the-roof is s'odesigned that the area o i-'t-hetop of thecenter pontoon is substantiall-yequal toithe area of vthe top surface ofthe declrpoition, andas previously stated, water 'iallingonto the'top orroof of the center pontoon is 'diverted directly to a drainage meansleading from same, instead of being discharged radially'rom'theperipheral edge of the center pontoon ontothe deck portion ofthe roof, Thus, by pretenting about oneehali' of the rainfall or snowvfall fromugetting onto thedeck portioml eliminate Aone-'haii of thepossible cause of the roof tippingsuiiiciently, due to anexoessive.water or snow load, to cause v-flarnageonimproper functioning of theroof. The annularplate girderfat the peripheral edge ci the deck portion, in addition to taking Vup circumferential compressions, servesvas a peripheral rim f orthe deck portion that effectively prevents theroof supporting .liquid ilom overflowing the-.decir lportion. Thevbottom of theenterpontooncan be of. anypreferredudesign. Intheparticular vform VVof my invention hereingillustrated,.the bottom ofthe center pon toonis .shapedsomewhat .like a frustrurn, so thattheloweredge of thcfperipheral rim of the center pontoon -..willyloe-disposed in Va lower horizontal plane f than ,th-amai or portion ofthe area of the bottom Aoigsaid pontoonwith the result thatthe .inneredge ofthe deckport-ion ofthe roof which is fattachedto theloyver edgeoi said 'peripheral rim,will-ibeadepressed further into the roof sup- 1porting-.liquidthan would beth-ecase' if Vthelower .edge-lof theperipheral-rim of 'the center pontoon were.leuelwithprdisposed in thesaine horizontal plane as the Ina-jor portionrof the area of the bottomci the center pontoon.

Figure l of the drawings is a fragmentary vertical transverse sectionalview of a oating tank roof embodying my present invention; and

Figure 2 is a top plan view of the structure illustrated in Figure l. Y

Referring to the accompanying drawings whic illustrate the preferredform oi my present invention, C designates theV center pontoon of theroof, B designates the flexible deck portion, A designates the annularcompression member attached to theouter or peripheral edge of the deckpontoon, and D designates a plurality of longitudinally adjustable,radially-disposed tension rods, attached to the center pontoon and tothe annular compression member A in such a way that most of the weightof said Vmember A is transferred to the peripheral rim 'i of the centerpontoon, for the purpose of sinking said rim into the liquid, to such anextent or degree, that the deck portion B will have a slope suicient todrain all Water therefrom into one or more outlets 9 whose intakes arelocated at or adjacent the point where the deck portion is attached tothe annular rim 'l' of the center pontoon. As previously stated, thecompression member A consists of an annular plate girder, whose web isdisposed vertically, the peripheraledge of the deck portion B beingrigidly attached to the bottom edge of said girder, t'hus'causing thegirder A to actas a peripheral for the deck portion B that prevents theroof supporting liquid from owing onto said deck portion.

The center pontoon C can be constructed in various ways., withoutdeparting from my invention. It is herein illustrated as consisting of aterior of same. The top or roof t' slopes down! wardly and inwardlytowards a vertically-disposed drain locatedat the center ofthe poneannular beam A, to which the outer peripheral edge'of the deck portion Bis attached, will be submerged in the liquid about Z'inches below thesurface of the liquid. The truss rods D are pro- Vvided withturnbuckles, so as to enable them to Vin a stable condition, due to itsvery eflicient drainage characteristics; and still another desirableVfeature of such av roofis that theV entire underside Voi same is at alltimes contacted by the liquid on which the roof floats, thus eliminatingthe possibility of a corrosive gas mixture toon C so as to cause rain orsnow which falls `discharge into the liquid in the tank onV which theroof iloats, or said drain can .be connected to an eduction pipe ofconventional construction, that leads to the exterior of the tank'. Theperipheral portion of the bottom 6 ofthe center collecting on theunderside of the roof in instances Where the liquid stored in the tankis ofV a corrosive nature;V Y Y Y Having thus describedV my invention,what claim as new and desire to secure by Letters Patent is: Y

A floating tank roof, comprising a center pontoon oi stiff construction,Vhaving a top, and bot* tom and a vertical rim between said top andbottom, a ilexibleirdeck portion surrounding said center pontoon andattached at its inner edge to the bottom edge portion ofthe rim on saidcenter pontoon, a stiff, annular girderV attached to the outer edge ofsaid deck portion and projecting upwardly therefrom, and tension membersattached at their outer ends to said annular Vgirder adjacent the bottomedge of same and attached at their inner ends to saidrcenter pontoon,ladjacentfthe top edgeiportion or same, for

`transferring part of the load of said annular pontoon isV preferablydeected slightly, as shown in Figure l, so as to makesaid bottomsubstantially irustrumeshaped. VThis form of construe tion is desirable,in'that it causes the bottom edge of the rim l', to Vwhich the innerperipheral edge of the deck portion B is attached, to sink farther intothe liquid than the major portion or" the areav of the bottom ii of thecenter pontoon, whereby the deck portion BV will be maintained in adownwardly pitched condition, whose angle or slope is sharp enough toinsure efcient drain,- age to the outlet 9 leading from said deckportion. Usually, the center pontoon and deck portion will be soproportioned. and combined that Y when the root is oating normally withno water or snow load, the bottom edge of the peripheral rim l of thecenter pontoon will be submerged Y in the liquid from 6 inches to l0inches below theV girder to the rim ofthe center pontoon, to mairb tainsaid deckY portion in Van inclined position, sloping downwardly towardsthe rim of theY center pontoon. Y 1

JOHN H. WIGGINS.

' Y REFERENCES CITED UNITED STATES PATENTS Number Y Name Date Y1,979,272 Kramer Nov. 6, 1934 2,008,686V Day A Y July 23, 1935 2,026,762Verner-- Jan. Y7, 1936 2,282,772 Wiggins May 12, 1942 2,287,212 Y'Wiggins June 23,1942 v2,321,058 Wiggins June a, 1943 2,359,416YHammeren Oct. rv3, 1944 Wiggins Y Oct. 2,

